This invention relates to static-conductive straps or bands. More particularly, this invention relates to a resilient static-conductive wrist band which may be easily converted between a self-supporting elongated configuration and an axially coiled configuration.
Static-conductive wrist straps or bands are well known in the art and find particular utility in the electronics assembly field where static electricity may cause serious damage to electronic components. These wrist bands are generally comprised of a fabric which is wrapped around a wrist and secured by a buckle or a loop-hook (Velcro) type attachment. Such an attachment provides means for adjusting the straps to assure a proper fit about the wearer's wrist. Fabric bands may also include elastic and be slid onto the wrist (rather than wrapped around the wrist) and therefore secured by the elastic feature.
In order to conduct static electricity away from the wearer, each of the fabric type wrist straps or bands include a conductive metal element secured on the inner surface of the fabric so as to come in contact with the wearer's skin. Alternatively, the required electrical contact is provided when the inner surface of the fabric is comprised of a conductive fiber (e.g., silver fibers) which are interwoven with the fabric. Some static-conductive wrist straps incorporate both the conductive element and the conductive fibers. The conductive element and/or conducted fibers are connected to a suitable ground. This connection generally employs a snap connector in electrical connection with the conductive element or conductive fibers with the snap connector being permanently afixed to the strap. A wire (i.e., a ground cord) is connected to the snap connector at one end and to the ground at the other end. Thus, any static charge built-up on the wearer is discharged to the ground by the wrist strap via the ground cord. The ground cord typically has a built-in current limiting resistor to prevent electrical shocks to the wearer.
While well suited for its intended purposes, prior art static-conductive wrist straps do suffer from certain drawbacks and deficiencies. For example, the fabric from the wrist straps will wear over time and generate particulates which are undesirable in areas such as "clean rooms" commonly found in the electronics industry. In the case of elastic wrist straps, the elastic straps tend to lose their elastic characteristics over time. Still another drawback of prior art devices is related to the safety of such devices. A wide variety of machines are used in electronics manufacturing, many of which are in areas where these static-conductive wrist straps are employed. If the wrist strap becomes caught in one of these machines while the machine is in operation and while the wrist strap is being worn, injury may result since the strap is not easily (i.e., quickly) removed from the wearer's wrist.